To see which companies are expanding, I used our data warehouse of online job postings1 to detect recent hiring2. Zynga and Playdom put out the most job postings over the last three months, with Watercooler, a Redwood City startup, finishing a distant third3:

While I focused on online social gaming companies, I checked to see which companies were showing interest in games for smartphones, and found not too many were mentioning the iPhone or Android platforms on their job posts. Outside of Zynga, Playdom and Popcap Games, none of the other companies had (many) job postings that mentioned the iPhone/iPad or Android platforms4:

(1) Data for this post is for U.S. online job postings through 7/25/2010 and is maintained in partnership with SimplyHired.com. We use algorithms to dedup job posts: a single job posting can contain multiple jobs and appear on multiple job sites.

(2) Online job postings are from thousands of sources, and there are no standardized data formats (e.g., a field for company name). I quickly normalized company names for this post, but the results remain at best approximations.

(3) Our data is for U.S. online job postings, so it does not reflect hiring for overseas subsidiaries (e.g., Playfish/EA is based in London). Moreover, we did not include social gaming companies based outside the U.S. In the Facebook ecosystem, some of the top gaming companies have headquarters in East Asia and South America.

(4) iPhone does seem to be the (smartphone) platform of choice for these companies. Of the Jan-to-Jul 2010 job posts placed by the companies listed above, 23% mentioned the iPhone/iPad and only 2% mentioned Android.